1. Field of the Invention
The present invention generally relates to tools and procedures for machining inspection and, more particularly, is concerned with a tool set and method for gauging and restoring concentricity between axial sections of a workpiece bore, such as a pressure port in a gun tube.
2. Description of the Prior Art
Testing the performance of ammunition involves test firing of the ammunition in a gun tube. Typically, a piezoelectric transducer mounted to the gun tube is used to detect the pressure generated therein by the ammunition. To install the transducer, a bore for providing a pressure-receiving port is fabricated in the gun tube in transverse relation to the axis of the tube. The bore normally contains a section having threads for threadably mounting the transducer within the bore. Fabrication of the bore is carried out by conventional machining operations, such as drilling and tapping the threaded bore.
Accurate machining of the bore is an absolute necessity. A bore having threads which are eccentric with respect to the wall portion of the bore into which the transducer tip extends can damage the transducer and bias the test data if there is preloading contact between the transducer tip and the bore wall portion. Further, the gun tube, which is an expensive component by itself, can be irretrievably lost if the eccentricity of the bore wall portion cannot be repaired. Therefore, to safeguard the equipment and ensure accurate test data it is essential that the bore be correctly machined.
Heretofore, it has been assumed that a tap guided by the drilling spindle of a machine used to drill the bore would follow the drilled bore. There has been no gauge available to measure the degree to which the resulting threads are concentric to the drilled bore. Neither has there been any device for correcting a transducer tip-receiving bore wall portion which is shown to be slightly eccentric.
Consequently, a need exists for equipment and procedures to overcome this deficiency.